White House Chief of Staff Denis McDonough and National Security Adviser Susan Rice met with a bipartisan delegation of senators late Tuesday for secret talks focused on foreign policy, several sources with knowledge of the discussion told Yahoo News.

Sen. Bob Corker, the top Republican on the Senate Foreign Relations Committee, alluded to the meeting on Wednesday, as the panel held a hearing on whether and how to overhaul the signature law of the global war on terrorism.

“I know we both attended sort of a discussion last night that I found to be one of the most bizarre I've attended on Foreign Relations on foreign policy in our country,” Corker said at one point, referring to himself and Sen. Bob Menendez (D.-New Jersey), the committee’s chairman.

“I know several of us were involved in a very bizarre discussion last night. This continues a very bizarre discussion,” Corker said at another point.

The Tennessee Republican did not say where or with whom the meeting took place (or why it was bizarre).

The White House later confirmed the meeting. National Security Council spokeswoman Caitlin Hayden said McDonough hosted "an informal discussion on national security issues," and that Rice and Deputy National Security Adviser Tony Blinken attended.

"This session was part of our ongoing efforts to consult with the Congress on issues important to the president," she said.

In addition to Corker and Menendez, Senators Susan Collins (R.-Maine), Carl Levin (D-Michigan), Jon Tester (D.-Montana) and John Walsh (D.-Montana) also attended the meeting, according to the sources, who requested anonymity.

The secret meeting came at a time of increasing bipartisan frustration with the White House over the 2001 law that authorized the war in Afghanistan and underpins policies like indefinite detention without charge and drone strikes.

“I look forward to engaging Congress and the American people in efforts to refine, and ultimately repeal, the AUMF’s mandate. And I will not sign laws designed to expand this mandate further,” Obama said at the time. “Our systematic effort to dismantle terrorist organizations must continue. But this war, like all wars, must end. That’s what history advises. That’s what our democracy demands.”

But one year later, the administration has yet to provide Congress with suggested specific changes to the law, much less with legislative language for rewriting it.

Senators including Corker let their frustration bubble over at Wednesday’s hearing.

“Has the administration proposed any refinement or any redefinition of the AUMF? I mean, have they provided us language in terms of what they think they need to handle the current situation?” Senator Ron Johnson (R.-Wisconsin) asked the State Department’s principal deputy legal adviser, Mary McLeod.